The closest known prior art U.S. Pat. No. 4,146,104 discloses a drive assembly comprising a power unit including a housing, wheel support means rotatably supported on the housing on bearing means encircling the housing, and geared transmission means directly coupling a power output shaft of the power unit to the wheel support means to cause it to rotate relative to the housing. The power unit is shown as an electric motor having an external power source with a statement in the specification that a fluid or internal combustion or other motor with an output shaft would be satisfactory as alternatives.
U.S. Pat. No. 3,897,843 discloses an electric motorized wheel wherein a pair of pneumatic tires are mounted on wheel hubs rigidly attached to a cylindrical motor frame having field coils mounted on the inner side with a motor rotor or armature rotatably supported within the motor frame. The rotor of the motor powered by an external power source drives an external planetary gear train having a reaction carrier mounted on an external base frame from which a single bearing for the complete assembly supports the entire wheel assembly.
U.S. Pat. No. 3,997,018 discloses a hydraulic wheel motor which drives a pneumatic rubber tire.
U.S. Pat. No. 3,631,659 discloses a lawnmower which is driven by a battery fed electric motor. A pair of side frames carry the cutters and roller adapted to roll over the lawn to be mowed. The batteries are accommodated in the roller which is in the form of a hollow cylinder.
U.S. Pat. Nos. 3,704,758, 3,820,617, 3,860,993, 3,893,532 and 3,948,332 show various forms of battery and electric motor powered golf bag carts all of which have the general configuration of a conventional pull cart having auxiliary fully exposed external battery motor and transmission components.
U.S. Pat. No. 672,713 discloses a horseless carriage employing a pair of drive wheels powered by electric motor and planetary gear trains which are mounted externally between the wheels.